Cblm Gasoline Fuel System

COMPETENCY BASED LEARNING MATERIALS

Sector:

AUTOMOTIVE/LAND TRANSPORT

Qualification:AUTOMOTIVE SERVICING NC II

Unit of Competency:

SERVICE ENGINE MECHANICAL COMPONENTS

Module Title:

SERVICING ENGINE MECHANICAL COMPONENTS

(GASOLINE FUEL SYSTEM)

Technical Education and Skills Development Authority

MADDELA INSTITUTE OF TECHNOLOGY

Maddela, Quirino

HOW TO USE THIS COMPETENCY-BASED LEARNING MODULE

Welcome to the Module: SERVICING COOLING SYSTEM. This module contains training materials and activities for you to complete.

The unit of competency "SERVICE ENGINE MECHANICALCOMPONENTS" contains the knowledge, skills and attitudes require for Automotive servicing National Certificate Level II (NC II ).

You are required to go through a series of learning activities in order to complete each learning outcome of the module. In each learning outcome there are Information Sheets, Resource Sheets and Reference Materials for further reading to help you better understand the required activities. Follow these activities on your own and answer the self-check at the end of each learning outcome. Get the answer key from your instructor and check your work honestly. If you have questions, please don’t hesitate to ask your facilitator for assistance.

Recognition of Prior Learning (RPL)

You may already have some or most of the knowledge and skills covered in this module because you have:

been working for someone already completed training in this area

If you can demonstrate to your trainer that you are competent in a particular skill or skills, talk to him/her about having them formally recognized so you won’t have to do the same training again. If you have qualifications or Certificates of Competency from previous trainings, show them to your trainer. If the skills you acquired are still relevant to this module, they may become part of the evidence you can present for RPL.

At the end of this learning material is a Learner’s Diary, use this diary to record important dates, jobs undertaken and other workplace events that will assist you in providing further details to your trainer or assessors. A Record of Achievement is also provided for your trainer to complete once you completed the module.

This learning material was prepared to help you achieve the required competency in Servicing Engine Mechanical Components. This will be source of information for you to acquire the knowledge and skills in this particular trade independently and your own pace with minimum supervision or help from your instructor.

In doing the activities to complete the requirements of this module, please be guided by the following:

TESDA-MITQA

SYSTEM

Auto Servicing NC II

Service Engine Mechanical System

Date Developed:May 2011

Document No.

Issued by: of 110

Developed by:

EDWARD P. ALIP Revision # 00

Talk to your trainer and agree on how you will both organize the training under this module. Read through the module carefully. It is divided into sections that cover all the skills and knowledge you need to successfully complete

Work through all information and complete the activities in each section. Read the information sheets and complete the self-check provided in this module.

Most probably your trainer will also be your supervisor or manager. He/She is there to support you and show you the correct way to do things. Ask for help.

Your trainer will tell you about the important things you need to consider when you are completing the activities and it is important that you listen and take notes.

You will be given plenty of opportunities to ask questions and practice on the job. Make sure you practice your new skills during regular work shifts. This way you will improve both your speed and memory and also your confidence.

Talk to more experienced work mates and ask for their guidance.

Use self-check questions at the end of each section to test your own progress.

When you are ready, ask your trainer to watch you perform the activities outlined in this module.

As you work through the activities, ask for written feedback on your progress. Your trainer keeps feedback/pre-assessment reports for this reason. When you have completed this learning material and feel confident that you have had sufficient knowledge and skills, your trainer will arrange an appointment with a registered assessor to assess you. The results of the assessment will be recorded in your Competency Achievement Record.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


LIST OF COMPETENCIES

`CODE NO. CORE COMPETENCIES

ALT723301 Perform Diesel Engine Tune Up

ALT723302 Perform Gas Engine Tune Up

ALT723303 Service Automotive Battery

ALT723304 Service Ignition System

ALT723305 Test and Repair Wiring/Lighting System

ALT723306 Perform Underchassis Preventive Maintenance

ALT723307 Service Starting System

ALT723308 Service Charging System

ALT723309 Service Engine Mechanical System

ALT723310 Service Clutch System

ALT723311 Service Differential and Front Axle

ALT723312 Service Steering System

ALT723313 Overhaul Manual Transmission

ALT723314 Service Brake System

ALT723315 Service Suspension System

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


MODULE CONTENT

QUALIFICATION: AUTOMOTIVE SERVICING NC II

UNIT OF COMPETENCY: SERVICE ENGINE MECHANICAL COMPONENTS

MODULE TITLE: SERVICING GASOLINE FUEL SYSTEM

INTRODUCTION: This module covers the principles of operation, servicing, and overhauling gasoline fuel system

NOMINAL DURATION: 16 HOURS

SUMMARY OF LEARNING OUTCOMES:

1. Explain fuel octane rating

2. Identify fuel pump types

3. Perform carburetor adjustment

4. Overhaul carburetor

ASSESSMENT CRITERIA:

1. Fuel octane rating information is accessed and used in accordance with manufacturer’s specification.

2. Data are gathered interpreted from American Petroleum Institute (API)

3. Safety measures are applied in dealing with fuel4. Fuel pump types are identified according to usage5. Classification of fuel pumps identified

6. Removed and installed fuel pumps according to service steps and procedures

7. Technical data are accessed and interpreted from manufacturer’s specification.

8. Tools & equipment are used in accordance with industry standard.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


9. Carburetor is overhauled in accordance with the required steps and procedures.

10. Appropriate tools are used in adjusting carburetors11. Carburetor adjustment specifications is obtained according to repair manual12. Adjusted carburetor according to required procedure

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


LEARNING OUTCOME #1EXPLAIN FUEL OCTANE RATING

CONTENTS:1. Properties of gasoline fuel2. Fuel octane rating 3. Safety measures in handling fuels


1. Fuel octane rating information is accessed and in accordance with manufacturer’s specification.

2. Data are gathered interpreted from American Petroleum Institute (API).

3. Safety measures are applied in dealing with fuel.

CONDITIONS: Students/Trainees must be provided with the following: WORKPLACE

1. Learning resource area2. Work station

EQUIPMENT/TOOLS:1. Engine mock-up (carbureted engine)

MATERIALS1. Learning media (modules, computer set, reference books, products

brochures)2. API manual3. Gasoline fuel

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


METHODOLOGIES:

1. Interactive discussion2. Self-paced instruction

3. Film viewing

ASSESSMENT METHOD:

1. Written exam2. Oral interview

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


LEARNING EXPERIENCES/ACTIVITIES

LEARNING OUTCOME # 1

EXPLAIN FUEL OCTANE RATING

LEARNING ACTIVITIES SPECIAL INSTRUCTION

1. Read information sheet # 9..1-1

Answer self-check # 9.1-11. “Properties of gasoline fuel and

fuel octane rating”

2. Read information sheet 9.1-2“Safety measures in handling gasoline fuels”

Answer self-check #9.1-2“Safety measures in handling gasoline fuels”

If you have some problem on the content of the information sheet don’t hesitate to approach your facilitator

If you feel that you are now kn owledgeable on the content of the information sheet you can now answer self-check provided in the module

Compare your answers to Answer key #9.1-1

Evaluate your own work using the performance criteria checklist

INFORMATION SHEET # 9.1-1

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


PROPERTIES OF GASOLINE FUEL

LEARNING OBJECTIVES:

After reading this information sheet, you should be able to:

1. Explain the properties of gasoline fuels;

2. Explain octane rating;

3. Explain the proper handling of gasoline fuels.

GASOLINE

Gasoline is a complex mixture of approximately 300 various ingredients, mainly hydrocarbons. Crude oil, as removed from the earth, is a mixture of hydrocarbon compounds ranging from gases to heavy tars and waxes. The crude oil can be refined into products, such as lubricating oils, greases, asphalts, kerosene, diesel fuel, gasoline and natural gas. The refining process separates the hydrocarbons so they can be used. During refining, the crude oil is heated by pumping it through pipes routed through hot furnaces and into a fractioning column. During the refining, the light hydrocarbon molecules are separated from the heavier ones. Located at different heights in the fractioning tube are draw pipes used to pull the desired petroleum materials out of the tower. The lightest products are taken from the top and so on. Before

its widespread use in the internal combustion engine, gasoline was an unwanted by- product of refining for oils and kerosene.

Figure 9.1-1A: Crude oil is the source for many different

products

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


Figure 9.1-1B: The refining process for crude oil.

Gasoline contains hydrogen and carbon molecules. The chemical symbol for this liquid is C8H15, which indicates that each molecules of gasolines contains 8 carbon atoms and 15 hydrogen atoms. Gasoline is a colorless liquid with excellent vaporation capabilities.

Oil refiners must meet gasoline standards set by the American Society for Testing and Materials (ASTM), the EPA, some state requirement, and their own company standards.

Two important factors affect the power and efficiency of a gasoline engine: Compression ratio and detonation. The higher the compression ratio, the greater the engine’s power output and efficiency. The better the efficiency the less fuel is consumed to produce a given power output. To have a high compression ratio requires an engine of greater structural integrity. Due to the use of unleaded gasoline, compression ratio now generally ranges from 8:1 to 10:1. High-performance engines may have higher compression ratios.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


Normal combustion occurs gradually in each cylinder. The flames front advances smoothly across the combustion chamber until all the air/fuel mixture has been burned. Detonation occurs when the flame front fails to reach a pocket of mixture before the temperature in that area reaches the point of self-ignition. Normal burning at the start of combustion cycle raises the temperature and pressure of everything inside the cylinder. The last part of the mixtures is both heated and pressurized, and the combination of those two factors can rise in to the point of self-ignition. At that moment, the remaining mixture burns almost instantaneously. The two flame fronts create a pressure wave between them that can destroy cylinder head gaskets, break piston rings and burn pistons and exhaust valves. When detonation occurs, a hammering, pinging, or knocking sound is heard. However, when the engine is operating at high speed, these sounds cannot be heard because of the noise from the engine and the road.

PROPERTIES OF GOOD GASOLINE FUEL FOR BETTER ENGINE PERFORMANCE

Many of the performance characteristics of gasoline can be controlled in refining and blending. The major factors affecting fuel performance are antiknock quality, volatility, sulfur content, and deposit control.

1. ANTI-KNOCK QUALITY

An octane number of rating was developed by the petroleum industry so the antiknock quality of a gasoline could be rated. The Octane number is measure of the fuel’s tendency not to experience detonation in the engine. The higher the octane rating, the less of a tendency the engine has to knock. By itself, the antiknock rating has nothing to do with fuel economy or engine efficiency.

Methods of determining gasoline Octane Number

Two methods are used for determining the octane number of gasoline: the Motor Octane Number (MON) method and the Research Octane Number (RON) method. Both use a laboratory single-cylinder engine equipped with a variable head and knock meter to measure knock intensity. A test sample of the fuel is used in the engine as the engine’s compression ratio and air/fuel mixture are adjusted to develop specific knock intensity. There are two primary standard reference fuels: isooctane and heptanes. Isooctane does not knock in an engine but is not used in gasoline because of

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


its expense. Heptane knocks severely in an engine. Isooctane has an octane number of 100. Heptane has an octane number of zero.

A fuel of unknown octane value is run in a special test engine, and the severity knock is measured. Various proportions of isooctane and heptane are run in the engine to duplicate the severity of the engine knock when the test fuel was run. When the knock cause by isooctane/heptane mixture matches that caused by the fuel being tested, the octane number is established by the percentage of isooctane in the mixture. For example, if 85% isooctane and 15% heptanes produced the same knock severity as the tested fuel, that fuel would be rated as having an octane rating of 85.

The octane rating required by law and the one displayed on gasoline pumps is the Antiknock Index (AK). It is the average of RON and MON. The antiknock index is stated as (R+M)/2.

The following factors affect knock:

Lean fuel mixture. A lean mixture burns slower than a rich mixture. This longer burning time causes higher combustion chamber temperature which promotes the tendency for unburned fuel in front of the spark ignition flame to detonate.

Over advanced ignition timing. Advancing the ignition timing induces knock. Retarding ignition timing suppresses knock.

Compression ratio. Compression ratio affects knock because cylinder pressures increase with the increase in compression ratio.

Valve timing. Valve timing that fills the cylinder with more air/fuel mixtures promotes higher cylinder pressures, increasing the chances for detonation.

Turbo charging and super charging. Both turbocharging and super charging force additional air into the engine’s cylinders, which induces higher cylinder pressures and promotes knock.

Coolant temperature. Hotspots in the cylinder or combustion chamber due to inefficient cooling or a damaged cooling system raise combustion chamber temperatures and promote knock.

Excessive carbon deposits. The accumulation of carbon deposit on the pistons, valves, and combustion chamber causes poor heat transfer from the combustion chamber. Carbon accumulation also artificially increases the compression ratio. Both conditions cause knock.

Air inlet temperature. The higher the air temperature when it enters the cylinder, the greater the tendency to knock.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


Combustion chamber shape. The optimum combustion chamber shape for reduced knocking is the hemispherical design with the spark plug located in the center of the combustion chamber. The hemi head allows for faster combustion, allowing less time for detonation to occur ahead of the flame front.

Octane number. Only when an engine is designed to take advantage of the higher octane gasoline can the value of the fuel be obtained. Most modern engines are design to operate efficiently with regular grade gasoline and do not require high-octane gasoline.

Most electronically controlled ignition systems have a sensor to detect if knock is occurring so the PMC can retard the ignition timing to prevent detonation.

One of the things to remember about high-octane fuel is that it burn slower than low octane gasoline; therefore, it is less likely to cause detonation.

2. VOLATILITY

Gasoline is very volatile. It readily evaporates so its vapor adequately mixes with air for combustion. Only vaporized fuel supports combustion. To ensure complete combustion, complete combustion must occur.

The volatility of gasoline is a significant factor in the following performance conditions:

Cold starting and warm-up. A fuel can cause hard starting, hesitation and stumbling during warm-up if it not readily vaporized. A fuel that vaporizes too easily in hot weather can form vapor bubbles in the fuel delivery system, causing vapor lock or a loss of performance. If a gasoline vaporizes while it is in a fuel line, it can stop the flow of gasoline through the line. Rather than flow through the lines the pressurized fuel will compress the vapor, not move it. Vapor lock can cause a variety of driveability problems.

Altitude. Gasoline vaporizes more easily at high altitudes, so volatility is controlled in blending according to the elevation of the place where the fuel is sold.

Crankcase oil dilution. A fuel must vaporize well to prevent diluting the crankcase oil with liquid fuel or break down the oil film on the cylinder walls, causing scuffing or scoring. The liquid eventually enters

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


the crankcase oil and results in the formation of sludge, gum, and varnish accumulation as well as the lubrication properties of the oil.

The difference in gasoline blends is the vapor pressure of the finished product. Gasoline blended for use in the summer is less volatile (does not burn as easily) than gasoline for use in the winter. Also, in high-altitude areas, fuels must be blended to have higher volatility because they can boil at lower temperatures. The definition of volatility assumes the vapor will remain in the fuel tank or fuel line and will cause a certain pressure based on the temperature of the fuel.

There are three methods of measuring the volatility of a fuel. The most common is the Reid vapor pressure (RVP) test. The RVP test is performed by placing a sample of gasoline into a sealed metal container that has a pressure measuring device attached to it. The container is submerged in heated (100o or 38oC) water. As the fuel is heated, it vaporizes.

Remember, the more volatile a fuel is, the easier it will vaporize. As the fuel vaporizes, it creates vapor pressure within the container. Fuels that are more volatile will create more pressure. The vapor pressure is measured in psi.

3. SULFUR CONTENT

Gasoline can contain some of the sulfur present in the crude oil. Sulfur content is reduced at the refinery to limit the amount of corrosion it can cause in the engine and exhaust system.

When the hydrogen in the hydrocarbons of the fuel is burned, one of the byproducts of combustions is water. Water leaves the combustion chamber as steam but can condense back to liquid and forms water droplets. Steam present in crankcase blowby also condenses to water.

When the sulfur in the fuel is burned, it combines with oxygen to form sulfur dioxide. This compound can combine with water to form sulfuric acid, a highly corrosive compound. This type of corrosion is the leading cause of exhaust valve pitting and exhaust system deterioration. With catalytic converters, the sulfur dioxide can cause the obnoxious odor of rotten eggs during engine warm up. To reduce corrosion caused by sulfuric acid, the sulfur content in gasoline is limited to less than 0.01%.

4. DEPOSIT CONTROL

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


Several additives are put into gasoline to control harmful deposits, including gum or oxidation inhibitors, detergents, metal deactivators, and rust inhibitors.

BASIC FUEL ADDITIVES

For many years, lead compounds, such as tetraethyl lead (TEL) and tetramethyl lead (TML) were added to gasoline to increase its octane rating. However, since the mid-1970s, vehicles have been designed to run on unleaded gasoline only. Leaded fuels are no longer available as automobile fuels.

Because of the deactivating or poisoning affect that lead has on a catalytic converter, gasoline are limited to a lead content of 0.06 gram per gallon. To achieve the desired octane rating, methycylopentienyl manganese tricarbonyl (MMT) is added to gasoline.

Not all additives improve the performance of gasoline. Some, such as olefins, have been identified as a cause of deposits on port fuel injectors.Gasoline additives have different properties and a variety of purposes.

Anti-Icing or Deicer

Isopropyl alcohol is added seasonally to gasoline as an anti-icing agent to prevent fuel line freeze-up in cold weather.

Metal Deactivators and Rust Inhibitors

Metal deactivators and rust inhibitors are used to inhibit reactions between the fuel and the metals in the fuel system that can form abrasive and filter-plugging substances.

Gum or Oxidation Inhibitors

Some gasoline fuels contain aromatic amines and phenols to prevent the formation of gum and varnish. During storage, harmful gum deposits can form due to the reaction of some gasoline components with each other and with oxygen. Oxidation inhibitors are added to promote gasoline stability. They help control gum, deposit formation and staleness.

Gum content is influenced by the age of the gasoline and its exposure to oxygen and certain metals such as copper. If gasoline is allowed to evaporate, the residue left can form gum and varnish.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


Detergents

The use of detergent additives in gasoline has been the subject of some public confusion. Detergent additives are designed to do only what their name implies clean certain critical parts inside the engine. They do not affect octane.

OXYGENATES

Oxygenates are compounds such as alcohol and ethers that contain oxygen in their molecular structure. Oxygenates improve combustion efficiency, thereby reducing polluting emissions. Many oxygenates also serve as excellent octant enhancers when blended with gasoline. Oxygenated fuels tend to have lower carbon monoxide emissions.

Figure 9.1-1C: Octane values of gasoline and common oxygenates

Ethanol

By far the most widely used gasoline additive today is ethanol (ethyl alcohol), or grain alcohol. Ethanol is a non corrosive and relatively non toxic alcohol made from renewable biological sources. Blending 10% ethanol into gasoline result in an increase of 2.5 to 3 octane points. With ethanol-blended gasoline, air toxics are about 50% less.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


In addition to octane enhancement, ethanol blending keeps the fuel injectors cleaner and less subject to corrosion due to the detergent additives found in most ethanol. Ethanol can loosen contaminants and residues that may have gathered in the vehicle’s fuel system.

All alcohols have the ability to absorb water. Water in the fuel system, originating from condensation, is absorb by the alcohol. This reduces the chance of fuel line freeze-up during cold weather. Ethanol also decreases carbon monoxide emission at the tailpipe due to the higher oxygen content of the fuel.

Ethanol blends are approved by all auto manufactures because of their clean air benefits. Older engine like non-hardened valve seats may need a lead substitute added to gasoline or ethanol blends to prevent premature valve seat wear. The chance of valve burning is decrease when ethanol is used because ethanol burns cooler than gasoline.

The biggest concern with using ethanol or methanol is they have low volatility and therefore can cause cold start problems or misfiring during warm up.

Methanol

Methanol is the lightest and simplest of the alcohols and is also known as wood alcohol. It can be distilled from coal or renewable sources, but most of what is used today is derived from natural gas.

Many automakers continue to warm motorist about using fuel that contains more than 10% methanol and co solvent by volume. Methanol is recognizes as being far more corrosive to fuel system components than ethanol, and this corrosion concerns automakers.

Methanol is also highly toxic and there are safety concerns with ingestion, eye or skin contact, and inhalation.

Methanol can be used directly as an automotive fuel but the engine must be modified for its use. It can also be used in flexible-fuel vehicles as M85, which is 85% methanol. However, this is not very common because car manufacturers are no longer supplying methanol powered vehicles.

In the future, methanol could be the fuel of choice for providing hydrogen to power fuel cell vehicles.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


MTBE

Methanol tertiary butyl ether (MTBE) has been used as an octane enhancer and supply extender because of its excellent compatibility with gasoline. Current U.S EPA restrictions on oxygenates limit MTBE in unleaded gasoline to 11% of volume. At that level, it increases pump octane (R+M/2) by 2.5 points. However, it is usually found in concentrations of 7% to 8% of volume. MTBE increase octane while reducing carbon monoxide emissions at the tailpipe and does it at a cost that makes it very attractive to gasoline marketers across the country.

Methanol can be used to make MTBE. However, MTBE production and use have declined because it has been found to contaminate ground water. As of 2004, MTBE is no longer used in gasoline and has been replaced by ethanol.

Other oxygenates are being tested as a replacement for MTBE. These include TAME (tertiary amyl methyl ether) and ETBE (ethyl tertiary butyl ether). Both have a slightly higher octane rating than MTBE and are manufactured from ethanol.

Aromatic Hydrocarbons

Aromatic hydrocarbons are petroleum-derived compounds including benzene, xylene, and toluene that are being used in some gasoline as octane boosters.

Reformulated Gasoline

MTBEs and ethanol are the most commonly used oxygenates for producing reformulated gasoline (RFG). By blending oxygen into the gasoline, the fuel requires less ambient oxygen for complete burning. Therefore, for the same carburetor of fuel injector settings, oxygenated gasoline produces a leaner air/fuel mixture and generates less carbon monoxide. Reformulated gasoline is also called cleaner-burning gasoline and costs slightly more than normal gasoline.

RFG can be used in existing engines with no modifications or special refueling facility requirements.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


SELF-CHECK # 9.1-1

TRUE OR FALSE

Directions

Read and analyze each statement carefully. Write TRUE if the statement is CORRECT, and write FALSE if it is WRONG. Write your answer on the space provided after each item. Good luck!

1. _____ Crude oil is a mixture of hydrocarbon compounds ranging from gases to heavy tars and waxes.

2. _____ The chemical symbol for gasoline is C8H16, which indicates that each molecules of gasolines contains 8 carbon atoms and 16 hydrogen atoms.

3. _____ The higher the compression ratio, the greater the engine’s power output and efficiency.

4. _____ Detonation occurs when the flame front fails to reach a pocket of mixture before the temperature in that area reaches the point of self-ignition.

5. _____ The lower the octane rating, the lesser of a tendency the engine has to knock.

6. _____ Two methods are used for determining the octane number of gasoline: the Motor Octane Number (MON) method and the Research Octane Number (RON) method.

7. _____The one displayed on gasoline pumps is the Antiknock Index (AKI). It is the average of RON and MON.

8. _____ A lean mixture burns slower than a rich mixture

9. _____ Retarding the ignition timing induces knock.

10. _____ Fuel does not cause hard starting, hesitation and stumbling during warm-up even if it not readily vaporized.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


10. _____ If a gasoline vaporizes while it is in a fuel line, it can stop the flow of gasoline through the line.

11. _____ To reduce corrosion caused by sulfuric acid, the sulfur content in gasoline is limited to less than 0.01%.

12. _____ Gum content is influenced by the age of the gasoline and its exposure to oxygen and certain metals such as copper. If gasoline is allowed to evaporate, the residue left can form gum and varnish.

13. _____ Methanol is the most widely used gasoline additive today.

14. _____ Blending 10% ethanol into gasoline result in an increase of 2.5 to 3 octane points.

15. _____ Methanol is the lightest and simplest of the alcohols and is also known as wood alcohol

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


ANSWER KEY # 9.1-1

1. TRUE

2. FALSE

3. TRUE

4. TRUE

5. FALSE

6. TRUE

7. TRUE

8. TRUE

9. FALSE

10. FALSE

11. TRUE

12. TRUE

13. FALSE

14. TRUE

15. TRUE

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:



PROPER HANDLING OF GASOLINE FUELS



1. Describe safety tips for handling gasoline fuels

Safety tips for handling gasoline:

Only store the minimum amount of gasoline needed. Store containers at room temperature, away from sources of heat or

ignition (e.g., sun, furnace, hot water tank, portable heaters, sparks, flames, etc.), and in a well ventilated area.

Remember, gasoline vapors are flammable, are heavier than air, and can travel long distances to an ignition source.

Never siphon gasoline by mouth. It is harmful and may cause death if swallowed. If ingested, do not induce vomiting. Get medical help immediately.

Do not smoke.

Avoid prolonged or repeated skin contact with fuel. Wash skin thoroughly with soap and water in case of contact.

Avoid breathing vapors or mists.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


Remove any clothing that is wet with fuel. Allow fuel to evaporate completely outdoors before washing. Thoroughly clean clothing before reuse.

Never use gasoline as a cleaning agent.

Safety Tips for Fueling Vehicles:

Identify and know how to operate emergency fuel cut offs. Know location and operation of fire extinguishers.

Always shut off engine while fueling.

Remove twists and small loops in the fuel delivery hose. These can cause the hose to fail or catch on bumpers as vehicles move around the pump islands.

Insert delivery hose nozzle firmly into the fill pipe of the vehicle. Maintain contact with the tank until the delivery is complete to reduce possibility of static electricity sparking.

Avoid spills by not over-filling the tank.

Reinstall the cap on the fill pipe when delivery is complete. Hang the hose in place on the pump.

Fill motorcycles slowly to prevent fuel from spilling and making contact with the hot engine.

Do not use the gas cap or other objects to hold the fuel delivery nozzle open.

Tips for Filling Gas Containers:

Turn off all sources of ignition (engine, lawn mower, etc.). Use only approved portable containers.

Place the container on the ground.

Keep the fuel nozzle in contact with the container to avoid static electricity.

Avoid breathing vapors while filling.

Fill the container slowly.

Do not over-fill a container. Leave 5% extra space to allow for expansion.

Tips Before Working on a Fuel Tank:

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


Clean and test tank to ensure that it is free of any flammable fuel or vapors before doing hot work on a tank. Verify with testing. When possible, replace the fuel tank rather than repair it. Repair tanks only in specialized shops.

1. Disconnect the battery and remove or turn off ignition sources before draining the tank.

2. Drain tanks only in well-ventilated areas, preferably outdoors.

3. Drain the fuel into containers that are approved for use with flammable liquids.

4. Do not drain gasoline tanks over or near inspection pits.

5. Use approved siphoning equipment to remove fuel. Do not use a hose.

6. If the fuel tank is removed from the vehicle or if welding will be carried out near the fuel lines, ensure that the lines are drained and the vapors are purged from the lines before the welding activities are started.

If vehicle tank leaks:

Keep vehicle outdoors. Ground and bond vehicle to a proper siphon tank.

Pump out remaining fuel into approved container.

SELF-CHECK # 9.1-1

TRUE OR FALSE

Directions


1. ___Do not over-fill a container. Leave 10% extra space to allow for expansion.

2. ___ Gasoline vapors are flammable, heavier than air, and can travel long distances to an ignition source.

3. ___Refueling can always be done without turning the engine off.

4. ___ Drain tanks only in well-ventilated areas, preferably outdoors.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


5. ___Use gasoline in cleaning engine parts

SCORE:

Trainee’s signature: Date:

Facilitator’s Signature: Date:

ANSWER KEY 9.1-1

1. FALSE

2. TRUE

3. FALSE

4. TRUE

5. FALSE

LEARNING OUTCOME #2IDENTIFY TYPES/CLASSIFICATION OF FUEL PUMP

CONTENTS:1. Types/classification of fuel pumps2. Operation of fuel pumps

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


3. Removing and installing Fuel pump


1. Fuel pumps types are identified according to usage2. Classification of fuel pumps identified3. Removed and installed fuel pumps according to service

steps and procedures.

CONDITION: Students/Trainees must be provided with the following:

WORKPLACE:1. Learning resource area2. Workstation

EQUIPMENT/TOOLS:1. Gasoline engines mock-up (with mechanical fuel pump and

electric fuel pump)2. Hand tools3. PPE

MATERIALS:1. Learning media (module, service manual, computer set,

CDs, Related books)

METHODOLOGIES:1. Self-paced instruction2. Demonstration

ASSESSMENT METHOD:1. Self-check2. Practical demonstration3. Oral interview

LEARNING EXPERIENCE/ACTIVITIES

LEARNING OUTCOME #2: TYPES/CLASSIFICATION OF FUEL PUMPS


If you have some problem

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


1. Read information sheet # 9.2-1

“Types/classification and operation of fuel pumps”

Answer self-check # 9.2-1

“Types/classification and operation of fuel pumps”

2. Perform job sheet #9.2-2

“Removing and installing fuel pump”

on the content of the information sheet don’t hesitate to approach your facilitator





TYPES OF FUEL PUMPS


TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:



1. Identify types of gasoline fuel system pumps;

2. Explain the operation of each type of fuel pump;

3. Describe the construction of each type of fuel pump;

4. Remove and install fuel pump according to service steps and procedures.

Fuel pumps are an integral component of any internal combustion automobile engine. Mechanical pumps and electric pumps are the two basic types of fuel pumps that automobiles use. Electric fuel pumps are quickly becoming more widely used than mechanical fuel pumps, but each type comes with its advantages and disadvantages.

TYPES

1. MECHANICAL FUEL PUMP

In mechanical fuel pump systems, a moving diaphragm creates a vacuum that sucks fuel to the engine. Diaphragm pumps are located on the engine and are operated by eccentric cams on crankshafts. Attached to the eccentric is a rocker arm that moves, flexing the diaphragm, which pumps fuel into the engine.

Figure 9.2-1A: A mechanical fuel pump is operated by the camshaft (look at the arrows)

2. ELECTRIC FUEL PUMP

Unlike mechanical fuel pumps that need to be located near the engine, electric fuel pumps can be placed anywhere in the car, but

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


http://www.ehow.com/cars/

http://www.ehow.com/about_4828154_different-types-fuel.html

http://www.ehow.com/cars/

work the best when they are installed near fuel tanks. Newer fuel pumps are often located within the fuel tanks themselves.

Figure 9.2-1B: An electric fuel pump is operated or energized by the power from the ignition system. Arrows show the flow of fuel.

PRESSURE

Mechanical fuel pumps are manufactured to operate at pressures between 4 and 6 lbs. per square inch (psi).

Electric fuel pumps, on the other hand, are capable of operating at pressures between 30 and 40 psi.

Types

Low pressure type-10 to 15 PSI

High Pressure type-30 to 45 PSI

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


FEATURES

There are two types of electric fuel pumps available to fuel pump consumers: High pressure electric fuel pumps and low pressure electric fuel pumps. When a fuel pump needs to be replaced, you should make sure that the correct pump is being installed as low pressure and high pressure electric fuel pumps look the same.

COMPARISONS

Probably the biggest difference between mechanical fuel pumps and electric fuel pumps is the pressure output difference. Automobiles that feature fuel injection systems employ electric fuel pumps. Automobiles that use carburetors typically utilize mechanical fuel pump technology.

Warnings

Fuel pumps that have leaks in them are dangerous, as leaking fuel can ignite. Regular maintenance should be scheduled to assure that a car's fuel pump is in proper working order. Care should be taken when handling fuels such as gasoline because it is flammable and harmful to touch or inhale.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


OPERATION OF THE MECHANICAL FUEL PUMP

The fuel pump delivers fuel from the tank to the engine under pressure. Mechanical fuel pumps are commonly used with carburetor type fuel systems. They are the oldest type of fuel pump, but they are still found on many vehicles. The mechanical fuel pump is mounted on the side of the engine block, using a gasket between the pump and the block to prevent oil leakage.

(C) (D)

Figures 9.2-1C, D, E: (C) Gaskets are used to prevent oil leakage. (D) A mechanical fuel pump is installed on the side of the engine (E) between the carburetor and the fuel tank

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


(E)

Since the mechanical pump uses a back-and-forth motion, it is a reciprocating pump. They are usually powered by an eccentric (egg- shaped lobe) on the engine camshaft. The parts of a basic mechanical fuel pump are the rocker arm, the return spring, the diaphragm, the diaphragm spring, and the check valves.

ROCKER ARM, also called an actuating lever, is a metal arm hinged in the middle. A small pin passes through the arm and fuel pump body. The outer end of the arm rides on the camshaft eccentric and the inner end operates the diaphragm.

RETURN SPRING keeps the rocker arm pressed against the eccentric. Without a return spring, the rocker arm would make a loud clattering sound, as the eccentric lobe hits the rocker arm.

DIAPHRAGM is a synthetic rubber disc clamped between two halves of the pump body. The core of the diaphragm is usually cloth that adds strength and durability. A metal pull rod is mounted on the diaphragm to connect the diaphragm with the rocker arm.

DIAPHRAGM SPRING, when compressed, pushes on the diaphragm to produce fuel pressure and flow. This spring fits against the back of the diaphragm and against the pump body.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


CHECK VALVES are used in a mechanical fuel pump to make the fuel flow through the pump. The check valves are reversed. This causes the fuel to enter one valve and exit through the other.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


Figure 9.2-1E: Parts of a mechanical fuel pump

The basic operation of a mechanical fuel pump operation is as follows:

INTAKE STROKE. The eccentric lobe pushes on the rocker arm. This action pulls the diaphragm down and compresses the diaphragm spring. Since the area in the pumping chamber increases, a vacuum pulls fuel through the inlet check valve.

OUTPUT STROKE. The eccentric lobe rotates away from the pump rocker arm. This action releases the diaphragm. The diaphragm spring then pushes on the diaphragm and pressurizes the fuel in the pumping chamber. The amount of spring tension controls the fuel pressure. The fuel is then forced to flow out of the outlet check valve.

Figure 9.2-1F: The inlet and outlet stroke of the mechanical fuel pump

Mechanical fuel pumps are classified as positive and non-positive diaphragm types. The mechanical positive fuel pump continues to pump fuel even when the carburetor bowl is filled; therefore, a method of bypassing the fuel back to the tank is required. The NONPOSITIVE type

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


is the one usually found in a gasoline engine. It delivers fuel to the carburetor only when it is needed for the requirements of the engine.

OPERATION OF THE ELECTRIC FUEL PUMP

An electric fuel pump, like the mechanical pump, produces fuel pressure and flow for the fuel-metering section of a fuel system. Electric fuel pumps are commonly used in gasoline fuel systems. They can be located inside the fuel tank (G) and (H) as part of the fuel pickup sending unit. Also, it can be located in the fuel line between the tank and the engine.

Figures 9.2-1G and H: (G) Exploded view of an In-tank Fuel pump, (H) In-line Fuel pump unit (top) and parts of the fuel pump

(below)

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


The advantage of an electric fuel pump has over the mechanical fuel pump is that an electric fuel pump can produce almost instant fuel pressure. A mechanical pump slowly builds pressure as the engine is cranked for starting. Most electric fuel pumps are a rotary type. This produces a smoother flow of fuel (less pressure pulsations) than a reciprocating, mechanical pump. Since most electric pumps are located away from the engine, they help prevent vapor lock. An electric fuel pump pressurizes all of the fuel line near the engine heat. This helps avoid vapor lock because pressure makes it more difficult for bubbles to form in the fuel. Electric rotary fuel pumps include the impeller, the roller vane, and the sliding vane types. They use a circular or spinning motion to produce pressure. An impeller electric fuel pump is a centrifugal pump, normally located inside the fuel tank. This pump used a small motor to spin the impeller (fan blade). The impeller blades cause fuel to fly outward due to centrifugal force. This produces enough pressure to move the fuel through the fuel lines. A roller vane electric fuel pump is a positive displacement pump (each pump rotation moves a specific amount of fuel). This pump is located in the main fuel line. Small rollers and an offset mounted rotor disc produce fuel pressure in the pump. When the rotor disc and rollers spin, they pull fuel to one side. The fuel is then trapped and pushed to a smaller area on the opposite side of the pump housing. This action squeezes the fuel between the rollers and the fuel flows out under pressure. The sliding vane electric fuel pump is similar to the roller vane pump, except vanes (blades) are used instead of rollers. Most rotary fuel pumps also have check valves and relief valves. The check valves keep the fuel from draining out of the fuel line when the pump is not in operation. A relief valve limits the maximum output pressure. Another type of electric fuel pump is the reciprocating electric fuel pump. This pump has the same basic action as a mechanical fuel pump; however, it uses a solenoid instead of a rocker arm to produce a plunger action. The reciprocating pump uses either bellows or a plunger. The solenoid turns on and off to force the bellows or plunger up and down. This action pushes fuel through the check valves and the fuel system. Both mechanical and electric fuel pumps can fail after prolonged operation.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


Figure 9.2-1I: Operation of an Electric Fuel pump

Indications of fuel pump problems are as follows:

LOW FUEL PUMP PRESSURE can be caused by a weak diaphragm spring, ruptured diaphragm, leaking check valves, or physical wear of moving parts. Low fuel pressure can make the engine starve for fuel at higher engine speeds.

HIGH FUEL PUMP PRESSURE, more frequent with electric fuel pumps, indicates an inoperative pressure relief valve. If the valve fails to open, both pressure and volume can be above normal. High fuel pump pressure can produce a rich fuel mixture or even flood the engine.

MECHANICALFUEL PUMP NOISE (clacking sound from inside the pump) is commonly caused by weak or broken rocker arm return spring or by wear of the rocker arm pin or arm itself. This noise can be easily

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


confused with valve or tappet clatter. To verify mechanical pump noise, use a stethoscope.

FUEL PUMP LEAKS are caused by physical damage to the pump body or deterioration of the diaphragm and gaskets. Most mechanical fuel pumps have a small vent hole in the pump body. When the diaphragm is ruptured, fuel will leak out of this hole. Fuel pump testing commonly involves measuring pump pressure and volume. Since exact procedures vary depending on the type of fuel system, refer to the manufacturer’s manual for exact testing methods. Sometimes, fuel pump vacuum is measured as another means of determining pump and line condition. Always remember that there are several other problems that can produce symptoms similar to those caused by a fuel pump.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


SELF-CHECK # 9.2-1

MULTIPLE CHOICES

DIRECTIONS

1. Read each statement carefully. 2. This is a multiple choice type of test. Choose the correct or the best answer and write ONLY THE LETTER that corresponds to your choice on the space provided before each item.3. Avoid erasures, make your module neat and clean. Good luck!

___1. The actuating lever of the mechanical fuel pump is directly operated by this shaft.

A. crankshaft

B. camshaft

C. output shaft

D. input shaft

___2. These pumps can be placed anywhere in the car, but work best when they are installed near fuel tanks. Newer fuel pumps are often located within the fuel tanks themselves.

A. automatic fuel pump

B. mechanical fuel pump

C. electric fuel pump

D. in-line fuel pump

___3. Mechanical fuel pumps are manufactured to operate at these pressures.

A. 4 to 6 psi

B. 2 to 3 psi

C. 6 to 8 psi

D. 8 to 10 psi

___4. The biggest difference between a mechanical fuel pump and electric fuel pump.

A. temperature output

B. pressure output

C. volume output

D. power output

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


___5. Mechanical fuel pumps are commonly used with this type of fuel system.

A. fuel injection type

B. port injection type

C. direct injection type

D. carbureted type

___6. This is installed between the mechanical fuel pump and the engine block to prevent oil leakage.

A. oil seal

B. gasket

C. spacer

D. washer

___7. A mechanical fuel pump operates in this type of motion.

A. rotary motion

B. oscillating motion

C. rocking motion

D. reciprocating motion

___8. A synthetic rubber disk inside the mechanical fuel pump that when compressed, produces pressure.

A. diaphragm

B. compressor

C. check valve

D. diaphragm spring

___9. It delivers fuel to the carburetor only when it is needed for the requirements of the engine.

A. electric pump

B. positive fuel pump

C. non-positive fuel pump

D. automatic fuel pump

___10. Electric fuel pumps are commonly used in this type of fuel system.

A. diesel fuel system

B. gasoline fuel system

C. LPG fuel system

D. carbureted fuel system

___11. All of the following are locations where electric fuel pumps can be installed except one.

A. inside the fuel tank

B. as a part of the fuel pick-up sending unit

C. in line between tank and engine

D. in the engine

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


___12. Most electric fuel pumps are of this type.

A. rotary type

B. reciprocating type

C. sliding vane type

D. roller type

___13. This part of the fuel pump keeps the fuel from draining out of the fuel line when the pump is not in operation.

A. intake valve

B. outlet valve

C. check valve

D. control valve

___14. Impeller-type electric fuel pumps are located in this part of the fuel system.

A. main fuel line

B. inside the fuel tank

C. in the engine

D. in the carburetor

___15. Which of the following is not a cause of low fuel pump pressure?

A. leaking check valve

B. ruptured diaphragm

C. weak diaphragm spring

D. inoperative pressure relief valve (stuck closed)

SCORE:

Trainee’s Signature: Date:


TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


ANSWER KEY # 9.2-1

1. B

2. C

3. A

4. B

5. D

6. B

7. D

8. A

9. C

10. B

11. D

12. A

13. C

14. B

15. D

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


JOB SHEET #9.2-2

REMOVING AND INSTALLING FUEL PUMPS

PERFORMANCE OBJECTIVE:

After reading this Job sheet, you must be able to:

1. Identify the tools, materials, and equipment in replacing mechanical fuel pump;

2. Test fuel pump as per standard procedure;

3. Replace fuel pump as per standard procedure;

4. Apply occupational safety and health standards.

SUPPLIES/MATERIALS, TOOLS AND EQUIPMENT:

EQUIPMENT:

1. Engine mock-up (carbureted engine)

2. PPE

TOOLS:

1. Screw drivers (flat/Philip)

2. Wrenches

3. Scraper

4. Pliers

5. pressure gauge

MATERIALS:

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


1. Fuel pump gasket

2. Sealant

3. Clean rags

The fuel pump is a single action diaphragm type. Because of their design, these pumps are serviced by replacement only. No adjustments or repairs are possible.

The pump is operated by an eccentric on the camshaft. On six cylinder engines, the eccentric acts directly on the pump rocker arm. On V8 engines, a pushrod between the camshaft eccentric and the fuel pump operates the pump rocker arm.

Some trucks have a fuel pump which has a metering outlet for a vapor return system; any vapor which forms is returned to the fuel tank along with hot fuel through a separate line. This greatly reduces any possibility of vapor lock by keeping cool fuel from the tank constantly circulating through the fuel pump.

FUEL PUMP TEST

Fuel pumps should always be tested on the vehicle. The larger line between the pump and tank is the suction side of the system and the smaller line, between the pump and carburetor is the pressure side. A leak in the pressure side would be apparent because of dripping fuel. A leak in the suction side is usually only apparent because of a reduced volume of fuel delivered to the pressure side.

1. Tighten any loose line connections and look for any kinks or restrictions.

2. Disconnect the fuel line at the carburetor. Disconnect the distributor-to-coil primary wire. Place a container at the end of the fuel line and crank the engine a few revolutions. If little or no fuel flows from the line, either the fuel pump is inoperative or the line is plugged. Blow through the lines with compressed air and try the test again. Reconnect the line.

3. If fuel flows in good volume, check the fuel pump pressure to be sure.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


4. Attach a pressure gauge to the pressure side of the fuel line. On trucks equipped with a vapor return system, squeeze off the return hose.

5. Run the engine at idle and note the reading on the gauge. Stop the engine and compare the reading with the figure listed in the Tune-Up Specifications chart or service manual. If the pump is operating properly, the pressure will be as specified and will be constant at idle speed. If pressure varies sporadically or is too high or low, the pump should be replaced.

6. Remove the pressure gauge.

The following flow test can also be performed:

1. Disconnect fuel line from carburetor. Run fuel line into a suitable measuring container.

2. Run the engine at idle until there is one pint of fuel in the container. One pint should be pumped in 30 seconds or less.

3. If flow is below minimum, check for a restriction in the line

The only way to check fuel pump pressure is by connecting an accurate pressure gauge to the fuel line at the carburetor level. Never replace a fuel pump without performing this simple test. If the engine seems to be starving out, check the ignition system first. Also check for a plugged fuel filter or a restricted fuel line before replacing the pump.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


FUEL PUMP REMOVAL

PROCEDURE:

1. Open the hood and disconnect the negative battery cable. Locate the fuel pump.

2. Before disconnecting the fuel lines, mark the fuel inlet, outlet and (if applicable) return lines near the fuel pump connections, to avoid confusion during installation

3. Squeeze the spring-type fuel line clips with a pliers in order to slide them back at free the line

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


4. Twist and pull the fuel lines from the pump

5. Disengage the fuel pump's actuating lever, then remove the pump

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


6. Remove the old gaskets and spacer

7. Clean the fuel pump seat on the engine and install the new fuel pump. Be sure to install the new gasket. Installation procedure is just the reverse of removal.

8. Start the engine and inspect any fuel leak.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


ASSESSMENT METHOD

PERFORMANCE CRITERIA CHECKLIST

Acceptability

Yes No

1. Fuel pump types are identified according to usage ______ ______

2. Fuel pump is tested as per service procedure ______ ______

3. Fuel pump is replaced as per service procedure ______ ______

4. Occupational safety and health standards observed ______ ______

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


Trainee’s signature: Date:


LEARNING OUTCOME #3OVERHAUL CARBURETOR

CONTENTS:1. Operating principles and components of the carburetor2. Carburetor operating systems

3. Procedure in overhauling carburetors


1. Technical data are accessed and interpreted from manufacturer’s specification.

2. Tools & equipment are used in accordance with industry standard.

3. Carburetor is overhauled in accordance with the required steps and procedures.


WORKPLACE:

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


1. Learning resource area2. Workstation

EQUIPMENT/TOOLS:1. Gasoline engine mock-up (carbureted)2. Hand tools3. PPE4. Air compressor


CDs, Related books)2. Cleaning solvent3. Carburetor repair kit

METHODOLOGIES:

1. Self-paced instruction2. Demonstration

ASSESSMENT METHOD:

1. Self-check2. Practical demonstration3. Oral interview

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


LEARNING EXPERIENCES/ACTIVITIES

LEARNING OUTCOME #3: OVERHAUL CARBURETOR


1. Read information sheet # 9.3-1

Operating Principles and Components of the Carburetor”

Answer self-check # 9.3-1


“Procedure in Overhauling Carburetor





TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


INFORMATION SHEET 9.3-1

OPERATING PRINCIPLES OF THE CARBURETOR



1. Identify the components of a carburetor;

2. Analyze the principles of operation of a basic carburetor.

THE CARBURETOR

The principles of supplying an engine with the right amounts of fuel and air have not changed over the years. However, stricter exhaust emission laws and the need for improved fuel economy have changed carburetor requirements. Today’s carburetors use numerous devices to alter the air-fuel ratio with changes in engine speed, temperature, and load.

A carburetor is basically a device for mixing air and fuel in the correct proportions (amounts) for efficient combustion. The carburetor bolts to the engine intake manifold. The air cleaner fits over the top of the carburetor to trap dust and dirt.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


When the engine is running, downward moving pistons on their intake strokes produce suction in the intake manifold. Air rushes through the carburetor and into the engine to fill this low pressure. The airflow through the carburetor is used to meter fuel and mix it with the air.

Figure 9.3-1A: A carburetor unit used by TOYOTA

BASIC CARBURETOR PARTS

A basic carburetor consists of: (see figure 9.3.3-1B next page)

1. CARBURETOR BODY- main carburetor housing

2. BARREL- air passage containing venture, throttle valve and main discharge tube

3. THROTTLE VALVE- airflow control valve

4. VENTURI- restriction or narrowed area inside the barrel

5. MAIN DISCHARGE TUBE- fuel passage between fuel bowl and barrel

6. FUEL BOWL-fuel storage area in body

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


Figure 9.3-1B: Basic parts of the carburetor

1. CARBURETOR BODY

The carburetor body is a cast metal housing for the other carburetor components. It contains cast and drilled passage for air and fuel. (In an actual carburetor the main discharge tube, venturi, fuel bowl and throttle valve, are normally made as part of the carburetor body.) A flange on the bottom of the body allows the carburetor to be bolted to the engine.

2. BARREL

The carburetor barrel, routes outside air into the engine intake manifold. It contains the throttle valve, venturi, and outlet end of the main discharge tube.

3. THROTTLE VALVE

The carburetor throttle valve is the disc shaped valve that controls airflow through the barrel. It is mounted on a shaft in the lower part of the barrel.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


When closed, the throttle valve restricts the flow of air and fuel into the engine. When the throttle is opened, airflow, fuel flow, and engine power increase.

Figure 9.3-1C shows how a car’s accelerator pedal and throttle cable control the throttle valve. When the driver presses the accelerator pedal, the throttle cable slides inside its housing. This swings the throttle valve open to increase engine power and speed.

Figure 9.3-1C: Driver’s accelerator pedal is connected to carburetor

throttle valve. Valve controls airflow and engine power output

When the accelerator pedal is released, a throttle return spring pulls the throttle valve closed. This returns the engine to a slow idle speed. Look at Figure 9.3-1D and E.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


(D) (E)

Figure 9.3-1D and E: Throttle valve position control air flow and amount in intake manifold. D—Throttle valve closed produces high vacuum in

manifold. Engine tries to draw air through carburetor, but cannot. E—Throttle opening allows airflow, reducing vacuum intake manifold.

4. VENTURI

A venturi produces sufficient suction to draw fuel out of the main discharge tube. Venturi action is illustrated in Figure 9.3-1F. Note how vacuum is highest inside the venturi. The narrowed airway increase air velocity, forming a low pressure area in the barrel

Figure 9.3-1F: The narrowed portion of the barrel produces venturi effect.

MAIN DISCHARGE TUBE

The main discharge tube uses venturi vacuum to feed fuel into the barrel and engine. Also

called MAIN FUEL NOZZLE, it is a passage in the carburetor body that connects bowl to the centre of the venturi. Refer to Figure 9.3-1G.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


Note how main discharge tube is located in carburetor body.

Figure 9.3-1G: The main discharge tube

FUEL BOWL

The carburetor fuel bowl holds a supply of fuel that is NOT under the fuel pump pressure. Several additional carburetor parts are mounted in the fuel bowl. See figure 9.3-1H.

Figure 9.3-1G: The float bowl contains the fuel and foater

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


BASIC CARBURETOR SYSTEMS

A carburetor system is a network of passages and related parts that help control the air-fuel ratio under a specific engine operating condition. Also called a CARBURETOR CIRCUIT, each system applies a speed, and load of the engine change.

For example, a petrol engine’s air-fuel mixture may vary from a rich 8:1 ratio to a lean 18:1 ratio. An automotive carburetor, using its various systems, must be capable of providing air-fuel ratios of approximately.

1. 8:1 for cold engine starting.2. 16:1 for idling.3. 15:1 for part throttle.4. 13:1 for full acceleration.5. 18:1 for normal cruising at highway speeds.

Note: Older cars not subject to strict emission control regulations, have a slightly richer air-fuel ratio. Late model cars have leaner carburetor settings to help reduce exhaust pollution.

The seven basic carburetor systems are the:

1. FLOAT SYSTEM-maintains supply of fuel in carburetor bowl

2. IDLE SYSTEM-provides a small amount of fuel for low speed engine operation

3. OFF-IDLE SYSTEM-provides correct air-fuel mixture slightly above idle speeds

4. ACCELERATION SYSTEM-squirts fuel into barrel when throttle valve opens and engine speed increases

5. HIGH SPEED SYSTEM-supplies lean air-fuel mixture at cruising speeds

6. FULL POWER SYSTEM-enriches fuel mixture slightly when engine power demands are high

7. CHOKE SYSTEM-provides extremely rich air-fuel mixture for cold engine starting

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


It is very important that you fully understand each of these systems. As each system is discussed, try to draw a “mental picture” of how a carburetor operates under the conditions described. This will help you when diagnosing and repairing carburetor problems.

1. FLOAT SYSTEM

The float system must maintain the correct level of fuel in the carburetor bowl. Since the carburetor uses differences in pressure to force fuel into the barrel, the fuel in the bowl must be kept at atmospheric pressure. The float system keeps the fuel pump from forcing too much petrol into the carburetor bowl.

Float system parts

The basic parts of a carburetor float system are the fuel bowl, float, needle valve, needle seat, bowl vent, and hinge assembly. Study the relationship of each part.

The carburetor float rides on top of the fuel in the bowl to open and close the needle valve. It is normally made of thin brass or plastic. One end of the float hinged to the side of the carburetor body. The other end is free to swing up and down.

Figure 9.3-1H. Basic parts of a float system. Float opens and

closes needle valve as fuel level falls and rises. Study part names.

The needle valve in the fuel bowl regulates the amount of fuel passing through the fuel inlet and needle seat. See Figure. The needle valve is usually made of steel. Sometimes, the end of the needle valve will have a soft (synthetic rubber) tip. The soft tip seals better than a metal tip, especially if dirt gets caught in the needle seat.

The carburetor float needle seat works with the needle valve and float to control fuel flow into the bowl. It is normally a brass that threads into the carburetor body.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


A bowl vent prevents a pressure or vacuum buildup in the carburetor fuel bowl. Without venting, pressure could form in the bowl as the fuel pump fills the carburetor. This could also cause vacuum form in the bowl as fuel is drawn out of the carburetor and into the engine.

Float system operation

When engine speed or load increases, fuel is rapidly drawn out of the fuel bowl and into the venturi. Illustrated in Figure 9.3-1I, this makes the fuel level and float drop in the bowl. The needle valve also drops away from its seat. The fuel pump can then force more fuel into the bowl.

As the level in the bowl rises, the float pushes the needle valve back into the seat. When the fuel level is high enough, the float closes opening between the needle valve and seat.

With the engine running, the needle valve usually lets some fuel leak into the bowl. As a result, the float system maintains a stable quantity of fuel in the bowl. This is very important because the fuel

level in the bowl can affect the air-fuel ratio.

Figure 9.3-1I: Basic operation of the float system

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


2. IDLE SYSTEM

A carburetor or idle system provides the engine’s air-fuel mixture at speeds below approximately 800 rpm or 30 km/h.

When an engine is idling, the throttle valve is almost closed. Airflow through the barrel is too restricted to produce enough vacuum in the venturi. Venturi vacuum cannot draw fuel out of the main discharge tube. Instead, the high intake manifold vacuum BELOW the throttle valve and a separate idle circuit are used to feed fuel into the barrel.

Idle system parts

The fundamental parts of a carburetor idle system include a section of the main discharge tube, a low speed jet, idle air bleed, bypass, idle passage economizer, idle port, and an idle mixture screw. These parts are illustrated in Figure 9.3-1J.

The low speed jet is a restriction in the idle passage that limits maximum fuel flow in the idle circuit. It is placed in the fuel passage before the idle air bleed and economizer.

The idle air bleed works with the economizer and bypass to add air bubbles to the fuel flowing to the idle port. As shown in the figure, the air bubbles help break up or atomize the fuel. This makes the air-fuel mixture burn more efficiently once in the engine.

The idle passage carries the mixture of liquid fuel and air bubbles to the idle screw port.

The idle screw port is an opening into the barrel below the throttle valve.

The idle mixture screw allows adjustment of the size of the opening in the idle screw port.

Figure 9.3-1J. Idle system feeds fuel when throttle is closed for low engine speed operation. High

vacuum below throttle pulls fuel out idle port. Mixture screw allows adjustment of mixture at idle. Air bleed helps premix air and fuel

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


Turning the idle screw IN reduces the size of the idle port and amount of fuel entering the barrel. Turning the idle screw OUT usually increases fuel flow and enriches the fuel mixture at idle.

Most modern carburetors have sealed idle mixture screws that are NOT normally adjusted. The idle mixture screws are covered with metal plugs, as pictures in Figure 9.3.3-1K. This prevents tampering with the factory setting of the idle mixture.

The idle screw adjustment of today’s carburetors is very critical to exhaust emissions.

Idle system operation

For the idle system to function, the throttle valve must be closed. Then, high intake manifold vacuum can draw fuel out of the idle circuit. Refer to Figure 9.3-1K.

At idle, fuel flows out of the fuel bowl, through the main discharge, and into the low speed jet. The low speed jet restricts maximum fuel flow.

At the bypass, outside air is drawn into the idle system. This partially atomizes the fuel. As the fuel and air bubbles pass through the economizer, the air bubbles are reduced in size to further improve mixing.

The fuel and air mixture then enters the side screw port. The setting of the idle screw controls how much fuel enters the barrel at idle.

Figure 9.3-1K. Modern idle mixture screws are covered with metal plugs. This prevents tampering which would upset mixture and increase exhaust emissions.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


3. OFF-IDLE SYSTEM

The off-idle system, often termed the PART THROTTLE CIRCUIT, feeds more fuel into the barrel when the throttle valve is partially open. Look at Figure 9.3.3-1L. It is an extension of the idle system. It functions ABOVE approximately 800 rpm (30 km/h).

Without the off-side system, the fuel mixture would become too lean slightly above idle. The idle circuit alone is not capable of supplying enough fuel to the airstream passing through the carburetor. The off-idle circuit helps supply fuel during transition (change) from idle to high speed. Refer to Figure 20-12.

Off-idle system operation

The off-idle system begins to function when the driver presses lightly on the accelerator pedal and cracks open the throttle valves. As the throttle valves swing open, they expose the off-idle ports to intake manifold vacuum. Vacuum then begins to draw fuel out of idle screw port and the off-idle ports. This provides enough extra fuel to mix with the additional air flowing around the throttle valves.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


Figure 9.3-1L. Off-idle system feeds fuel when throttle is opened slightly. It adds a little extra fuel to the extra air flowing around throttle valve.

4. ACCELERATION SYSTEM

The carburetor’s acceleration system, like the off-idle system, provides extra fuel when changing from the idle circuit to the high speed circuit (main discharge).

The acceleration system SQUIRTS a stream of extra fuel into the barrel whenever the accelerator pedal is pressed (throttle valves swing open). This is illustrated in Figure 9.3-1M.

Figure 9.3-1M. Accelerator pump systems squirts fuel into air horn every time is opened. This adds fuel to rush of air entering engine and prevents

temporary lean condition. Study part names.

Without the acceleration system, too much air would rush into the engine as the throttle is quickly opened. The mixture would become too lean for combustion and the engine would HESITATE or STALL.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


Acceleration system parts

The basic parts of a carburetor acceleration system are the pump linkage, accelerator pump, check ball, pump reservoir, pump check weight, and pump nozzle. These parts are given in Figure 9.3-1N.

The accelerator pump develops the pressure to force fuel out of the pump nozzle and into the barrel. There are two types of accelerator pumps; piston and diaphragm. See Figures 9.3-1N and 9.3-1O.

Figure 9.3-1N: Most accelerator pump systems use mechanical linkage from throttle lever. When driver presses accelerator pedal for

acceleration, both the throttle valve and piston pump are actuated.

Figure 9.3-1O: Cutaway view of carburetor using a diaphragm type accelerator pump

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


.

Acceleration system operation

When the driver presses the accelerator pedal, the throttle valves swing open. This causes the accelerator pump piston or diaphragm to compress the fuel in the pump reservoir.

Accelerator pump pressure closes the pump check ball and fuel flows toward the pump check weight. Pressure lifts the pump check weight off its seat and fuel squirts into the carburetor barrel, as it from a TOY SQUIRT GUN.

A spring is used on the accelerator pump assembly to produce smooth, steady flow of fuel out the pump nozzle. Throttle opening compresses the spring. Then the compressed spring pushes on the pump piston to pressure the fuel and produce prolonged fuel flow.

As the accelerator pedal is released, the pump piston or diaphragm retracts. This closes the discharge check weight and opens the pump check ball. Fuel flows out of the bowl to refill the accelerator pump reservoir. The system is then ready to spray another stream of

fuel into the barrel when the car accelerates.

Figure 9.3-1P shows an auxiliary acceleration system. It supplements the main acceleration system when the engine is cold.

Figure 9.3-1P: Auxiliary accelerator pump system is

sometimes used to aid conventional mechanical pump system. Thermal-vacuum valve

is open when engine is cold. This allows engine vacuum to

operate vacuum-operated accelerator pump

5. HIGH SPEED SYSTEM

The carburetor’s high speed system, also called MAIN METERING SYSTEM, supplies the engine’s air-fuel mixture at normal cruising

speeds, Figure 9.3-1Q. This circuit begins to function when the throttle valves are open wide enough for venturi action. Airflow through the carburetor must be

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


relatively high for venturi vacuum to draw fuel out of the main discharge tube.

The high speed system provides the leanest, most fuel efficient air-fuel ratio. It functions from about 30 to 90 km/h or 2000 to 3000 rpm.

Figure 9.3-1Q High speed system is simple. Main jet control fuel flow and mixture. At consists of a high speed jet, main discharge passage, emulsion tube, air bleed, and venturi.

High speed system operation

When engine speeds is high enough, airflow through the carburetor forms a high vacuum in the venturi. The vacuum draws fuel through the main metering system.

Fuel flows through the main jet which meters the amount of petrol entering the circuit. Then, the fuel flows into the main discharge tube and emulsion tube.

The emulsion tube causes air form the air bleed to mix with the fuel. The fuel, mixed with air, is finally drawn out of the main nozzle (main discharge tube) and into the engine.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


6. FULL POWER SYSTEM

The carburetor full power system provides a means of enriching the fuel mixture for high speed, high power conditions. This circuit operates, for example, when the driver presses the accelerator pedal to pass another vehicle or to climb a steep hill. A simplified illustration of a full power system is given in Figure 9.3-1R.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


Figure 9.3-1R: High speed-full power system enriches high speed circuit when needed. When the accelerator pedal is pushed down for full power, throttle linkage acts on metering rod linkage. Metering

rod is lifted out of main jet to add more fuel to the mixture.

The full power system is usually an addition to the main metering system. Either a metering rod or a power valve (jet) can be used to provide a variable, high speed air-fuel ratio.

Metering rod action

A metering rod is a stepped rod that moves in and out of the main jet to alter fuel flow.

As shown in Figure 9.3-1S, when the metering rod is down inside the jet, flow is restricted and a leaner fuel mixture results. When the metering rod is pulled out of the jet, more fuel can flow through the system to enrich the mixture for more power output.

Figure 9.3-1R: Metering rod action. A—Metering rod lowered into jet. Less fuel can flow through jet, leaning mixture. B—Metering rod pulled out of jet. This allows more fuel flow through jet, enriching mixture.

Either mechanical linkage or engine vacuum can be used to operate a metering rod

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


The metering rod can be linked to the throttle lever. Then, whenever the throttle is opened wide, the linkage lifts the metering rod out of the jet.

A metering rod controlled by engine vacuum is connected to a diaphragm. At steady speeds, power demands are low and engine vacuum is high. The opposite is true under heavy power demands (wide open throttle); intake manifold vacuum drops. This vacuum-load relationship is ideal for controlling a metering rod or power valve.

Power valve action

A power valve, also known as an ECONOMISER VALVE, performs the same function as a metering rod; it provides a variable high speed fuel mixture. A power valve consists of a fuel valve, a vacuum diaphragm, and a spring.

Look at Figure 9.3-1T. The spring holds the power valve in the normally open position. A vacuum passage runs to the power valve diaphragm. When the power valve is open, it serves as an extra jet that feeds fuel into the high speed circuit.

Figure 9.3-1T: Power valve serves same function as metering rod. It enriches mixture under high load, low intake manifold vacuum conditions. When vacuum is low, spring opens power valve. Extra fuel can then flow through valve and into main discharge.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


When the engine is cruising at normal highway speeds, engine intake manifold vacuum is high. This vacuum acts on the power valve diaphragm and pulls the fuel valve closed, figure below. No additional fuel is added to the main metering system under normal driving conditions.

Figure 9.3-1U: Power valve action. (Left)—High vacuum, low power output closes power valve by pulling on diaphragm. No extra fuel enters main system. (Right)—Engine power output is high, causing intake manifold vacuum to drop. This allows spring to open power valve for more power

CHOKE SYSTEM

The choke system is designed to supply an extremely rich air-fuel ratio to aid cold engine starting.

For the fuel mixture to burn properly, the fuel entering the intake manifold must atomize and vaporize. When the engine is cold, the fuel entering the intake tends to condense into a liquid. As a result, not enough fuel vapors enter the combustion chambers and the engine could miss or stall when cold. A choke is used to prevent this lean condition.

Choke system parts

A choke system has a choke valve (plate), thermostatic spring, and other parts depending upon choke design. See Figure 9.3-1V.

Figure 9.3-1V: Basic choke system parts. Thermostatic spring is main control of choke operation. When engine is cold, spring closes choke. High vacuum below choke pulls large amount of fuel out of main discharge. When engine warms, hot air causes spring to

open choke. Vacuum piston cracks choke upon engine starting to prevent flooding.

The choke valve is a butterfly (disc) type valve located near the top of the carburetor barrel.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


When the choke valve is closed, it blocks normal airflow through the carburetor. This causes high intake manifold vacuum to form below the choke valve. Vacuum pulls on the main discharge tube even though air is not flowing through the venturi. Fuel is drawn out to prime the engine with extra fuel.

SELF-ASSESSMENT 9.3-1

MULTIPLE CHOICE

DIRECTIONS


___1. What is the function of the carburetor?

A. to mix air and fuel

B. to mix air and fuel at the right amount

C. to add power to the engine

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


D. to prolong engine life

___2. The restriction or narrowed area inside the barrel of a carburetor.

A. venturi

B. main discharge nozzle

C. throttle

D. fuel bowl

___3. When this valve inside the carburetor opens, engine power increases.

A. control valve

B. intake valve

C. exhaust valve

D. throttle valve

___4. Air-fuel ratio for cold engine starting.

A. 8 : 1

B. 16 : 1

C. 15 : 1

D. 13 : 1

___5. This system provides a small amount of fuel for low speed engine operation.

A. off-idle system

B. idle system

C. low idle system

D. minimum idle system

___6. This system enriches fuel mixture slightly when engine power demands are high.

A. full power system

B. acceleration system

C. high speed system

D. power system

___7. This system is used especially in the morning when the engine requires a richer mixture for easy starting.

A. choke system


C. rich mixture system

D. lean mixture system

___8. The correct level of fuel in the carburetor bowl is maintained by this system.

A. fuel bowl

B. floater

C. float system

D. fuel system

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


___9. This part is directly operated by the driver to activate the carburetor.

A. accelerator system

B. accelerator pedal

C. accelerator cable

D. accelerator mechanism

___10. It provides a lean air-fuel mixture at cruising speeds.

A. high speed system


C. full power system

D. lean air-fuel system

SCORE:



ANSWER KEY 9.3-1

1. B

2. A

3. D

4. A

5. B

6. A

7. A

8. C

9. B

10. A

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


JOB SHEET#9.3-2

OVERHAULING CARBURETOR

PERFORMANCE OBJECTIVES:

After reading this job sheet, you must be able to:

1. Prepare appropriate the tools, materials, and equipment needed in overhauling carburetor;

2. Clean and inspect carburetor parts as per service manual instructions;

3. Overhaul carburetor as per service procedure;

4. Apply occupational safety and health standards.


TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


EQUIPMENT:

1. PPE

2. Air compressor

3. Container

TOOLS:

1. Basic Hand tools

2. Soft brush

MATERIALS:

1. Learning media (module, service manual, related books, computer set, CDs)

2. Cleaning solvent

3. Repair kit

4. Sealant

5. Rags

NOTE: Read this procedure completely before starting

CARBURETOR REMOVAL

PROCEDURE:

1. Before removing the carburetor, check the operation of the idle solenoid valve. Remove the wire from it, then turn on the ignition (do not start the car). Touch the wire to the electrical connector on the idle solenoid valve. You should hear a distinct "click." If you hear the click, the valve is okay -- otherwise, it must be replaced. Turn the ignition off.

2. Disconnect the hoses and blow-by tube from the oil filler to the air cleaner, then remove the air cleaner and set it aside.

3. Detach the fuel hose from the carburetor and quickly plug it to minimize fuel leakage (a pencil works great for this).

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


4. Detach vacuum hoses if you have them; if you have no vacuum hoses, remove the caps from the vacuum ports on the carburetor.

5. Disconnect the wire to the automatic choke heating element ( #40 in the exploded illustration)

6. Disconnect the wire to the electromagnetic cutoff valve (#16 in the exploded illustration).

7. Loosen the screw in the accelerator cable barrel clamp; pull the cable forward out of the pin. Stow the cable barrel clamp and screw in a safe place so you can find them later (small parts).

8. Remove the distributor cap to provide access, then remove the two nuts (13mm) from the studs on the carburetor flange. Make sure to have the front nut brightly lit so you can see what you're doing.

9. Remove the carburetor and gasket; there will be a new gasket in your kit, but try to maintain the integrity of the old gasket, "just in case." Stow the two nuts in a safe place.

10. Put a rag into the open intake manifold to keep foreign material out.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


Carburetor Nomenclature

Ref. No.

Part Ref. No.

Part

1 Fillister head screw and lock washer (upper body (5)

23 Accelerator pump diaphram spring

2 Spring washer 24* Accelerator pump diaphram

3 Carburetor upper part 25 Cotter pin

4* Float valve washer 26 1-mm (.040 in.) thick washer (2)

5* Float valve 27 Connecting rod spring

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


6* Gasket, carburetor body 28 Connecting link

7* Float pin retainer 29 Adjustable bell crank

8 Float and pivot pin 30 Circlip

9 Air correction jet with emulsion tube

31 Adjusting segment

10 Carburetor body 32 Accelerator pump cover

11 Pilot air drilling 33 Screw

12 Auxiliary air drilling 34 Pilot jet

13 Bypass screw 35 Vacuum diaphram cover

14 Main jet cover plug 36 Oval head screw (3)

15* Main jet cover plug seal 37 Vacuum diaphragm spring

16 Electromagnetic cutoff valve 38* Vacuum diaphragm

17 Main jet 39 Plastic cap

18 Volume control screw and O-ring 40 Choke heating element

19 Fast idle lever 41 Cover retaining ring

20 Throttle valve lever 42 Retaining ring spacer (3)

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


21 Throttle return spring 43 Small fillister head screw (3)

22 Accelerator pump injector

*Included in the tune-up kit.

CARBURETOR DISASSEMBLY

PROCEDURE:

1. Use the exploded view as a guide. The numerical sequence shown there can generally be followed to disassemble the unit far enough to permit cleaning and inspection.

Note: You will be removing a number of small parts in this process. Work with extra care!

2. Having a small container (like a half-pint glass jar) at ready, remove the main jet plug on the left side of the carburetor and drain the gasoline out of the carburetor bowl into your container. Stow the plug where you can find it.

3. Remove the five fillister-head screws that hold the upper part of the carburetor (3) to the body (10) and remove the upper part. Remove the gasket; your carburetor kit should have a new one, but again, try to remove the old gasket carefully. You can still use it just in case you have bought the wrong repair kit.

4. Remove the float needle valve (5) from the underside of the upper part of the carburetor. There should be a new one in your kit. This valve gets a lot of work -- you should always replace it.

Note: Compare the new float valve with the old one. They MUST be the exactly the same!

5. For future reference (i.e., reassembly), note the arrangement of the float pin retainer (7) and the float pivot pin (8) relative to the float (8); remove the float assembly and store away carefully. There will be a new pin retainer (7) in your kit; be sure to note which way it goes (see the

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


exploded view). The bow in the retainer MUST be pointing toward the front of the car (i.e., toward the fan shroud).

6. Remove the electromagnetic cutoff valve (16) from the left side of the carburetor with a 17mm wrench.

7. Remove the bypass screw (13) and the volume control screw (18) from the left side of the carburetor.

Note: The manuals say that you should not remove the volume control screw, as it is set at the factory. If you are servicing an old carburetor, you need to remove the volume control screw for it to be cleaned. For easier installation, count the number of turns when you remove it.

8. Inspect the O-rings on the bypass screw and the volume control screw for wear. If they are defective, replace them.

9. Reach through the jet plug hole (main jet cover plug (14) which was removed previously) with a screwdriver and remove the main jet (17). The size of the jet is stamped on the top. You may want to change the jet size in accordance with your preference.

10. Remove the air correction jet (9)(it screws out vertically).

11. Remove the pilot jet (34) (sometimes called the "idle" jet) from the right side of the carburetor. Remove the little cover and jet that are at the ten-o'clock position from the pilot jet.

12. Remove the various other jets and adjustment screws from the carburetor body and store them away carefully. You will clean these and replace them. Inspect all jets, adjustment screws, and the holes they came from for wear.

CAUTION: Brass tube type jets are not removable.

13. Disassemble the accelerator pump (32) and linkage (28) by removing the four screws (33). There will be a new accelerator pump diaphragm (24) in your kit.

14. Check the throttle valve shaft assembly for lateral movement (side-

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


to-side) in the throttle shaft. If you find such movement, the shaft hole is out-of-round and you will be getting air in-leakage. This is very serious; it is likely that the rest of the carburetor isn't in very good condition. If you discover this problem, it is better to buy a new carburetor.

Note: Some auto parts supplier can offer you a complete rebuild at a competitive price.

15. Disassemble the automatic choke assembly (40) by removing the three screws (43) in the cover retaining ring (41). Be careful to make sure the three retaining ring spacers (42) will not be lost.

16. Remove the choke vacuum diaphragm cover (35) by removing the three oval-head screws (36).

17. Remove the vacuum diaphragm (38) and spring (37)

CARBURETOR CLEANING

PROCEDURE:

1. Cleaning must be done with carburetor disassembled.

2. Soak parts all metal parts in carburetor cleaning solvent (or lacquer thinner) long enough to soften and remove all foreign material. Use an old toothbrush to clean the carburetor body.

CAUTION: Always wear safety glasses when using cleaning solvents or compressed air. Do not allow cleaning solvent to come in contact with skin. When using compressor, be sure to hold the parts, they may fly when hit by the air.

Note: Do not soak the choke heating element, pump diaphragm, float, vacuum diaphragm, or any other rubber or plastic parts in carburetor solvent.

Make certain the throttle body (carburetor throat, etc.) is free of all hard carbon deposits. Wash off in suitable solvent, like lacquer thinner, which is basically toluene.

Blow out all passages in castings with compressed air. Check

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


carefully to ensure thorough cleaning of obscure areas. Do NOT use a wire or similar object to "clean" orifices!

Make sure all jet orifices are clean and free of obstructions, using compressed air. Again, DO NOT use wire or other objects to clean the jets!

3. Prepare parts for re-assembly.

CARBURETOR RE-ASSEMBLY

Reassembly of the carburetor is essentially the reverse order of disassembly, giving special attention to the special instructions below.

Replace the Following Parts

Accelerator pump diaphragm (24) Choke vacuum diaphragm (38)

Float needle valve and gasket (4 & 5) (See note below.)

Float pin retainer (7)

Carburetor body-to-cover gasket (6)

Main jet plug seal (15)

Volume control screw O-ring (18)

Carburetor-to-intake manifold gasket

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


RE-ASSEMBLY INSTRUCTION:

PROCEDURE:

1. Check the float valve for binding and leakage. It should not be possible to blow air through the valve while the needle is pressed lightly onto its seat.

2. Check the float for leaks by immersing it in hot water. If bubbles appear, replace the float.

3. Check the float lever for a worn spot (depression) where it makes contact with the fuel inlet needle valve. Replace the float assembly, if necessary.

4. The proper float valve washer (4) must be used for the specific type of carburetor.

Note: It is very important that you install the correct needle seat gasket. This gasket sets the fuel height in the float bowl; erratic behavior may result if the gasket is not correct.

Important note regarding the float valve in SOME carburetor:

The float valve in some carburetor has a spring-loaded ball bearing in the end of the needle that impinges on the float. This little ball bearing MUST be in place. If it's not, the float bowl will overfill through the bowl vent down the throat of the carburetor, causing the fuel/air mixture to be WAY too rich - and of course the exhaust will spew out a lot of black smoke and the engine will not run.

4. Install the float pin retainer with the bow facing the front of the car (i.g., toward the fan shroud).

5. When installing the accelerator pump diaphragm (24) and spring, (23) make sure the larger end of spring is properly seated in the carburetor body cavity. Be sure to install the diaphragm with plunger toward pump cover. (See the exploded view.)

6. Be sure to use the correct body joint gasket; there will probably be several in your kit. Use the old one for comparison.

7. Check the electric heating element (40) in the automatic choke housing

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


http://www.vw-resource.com/Carbpic.html

for damage. If it is broken, distorted or "kinked", replace the assembly. The element can be checked with an ohmmeter or connected to a correct voltage battery for a few minutes to see if it warms up. (Be sure to ground the inside metal part of the housing in order to complete the circuit.)

8. When installing the choke assembly with spring and heater element, carefully rotate the assembly counterclockwise, making sure that the hook on coil end engages with the lever on choke shaft. Continue rotating approximately 1/8 turn more until the index marks align. Then, making sure the three retaining ring spacers are in place, tighten three retaining ring screws securely.

9. Turn the volume control screw (18) in until it seats lightly, then back it out 2-1/2 to 3 turns. The bypass screw (13) will have to be adjusted to give the proper idle with the engine running.

CARBURETOR INSTALLATION

PROCEDURE:

1. Install in reverse order of removal.

2. Lightly lubricate the choke valve shaft and throttle valve shaft with engine oil and the external linkage with molybdenum grease.

3. Using a new gasket, install the carburetor on the intake manifold flange.

Note: You will notice that the flange holes on the intake manifold which the carburetor rests on are slotted. This is so you can move the carburetor back and forth a bit (front-to-back) to assure that the accelerator pump linkage on the right side of the carburetor clears both the fan shroud at the front and the alternator body at the back. Both clearances are essential; if the accelerator pump linkage rubs on either end, the throttle lever will not be able to return all the way to the stepped cam, the result being an excessively high idle that cannot be controlled with the bypass screw.

4. Torque the retaining nuts on the bolts protruding through the intake manifold flange to 14 ft-lb using a torque wrench. Be careful that you don't tighten these nuts too much -- you may strip the stud out of the base of the carburetor.

5. Secure the fuel hose to the inlet nozzle on the carburetor with a new hose clamp.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


6. Pass the end of the accelerator cable through the cable pivot pin installed in the throttle lever. Pull it back tight (with the idle screw against the lowest step on the cam) and snug down the screw. You can use a small needle-nose vise grip to hold the end of the cable to the throttle lever while tightening the screw with your other hand).

7. The carburetor is now properly installed.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


ASSESSMENT METHOD


Acceptability

Yes No

1. Appropriate tools, materials, and equipment are used.

______ ______

2. Carburetor is removed from the engine as per service instruction manual

______ ______

3. Carburetor is disassembled and assembled as per required procedure

______ ______

4. Parts are cleaned and checked as per instruction ______ ______




TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


LEARNING OUTCOME #4 PERFORMING CARBURETOR ADJUSTMENT

CONTENTS:1. Adjustments in carburetors;2. Procedure in adjusting carburetors;3. Specifications in carburetor adjustment


1. Appropriate tools are used in adjusting carburetors2. Carburetor adjustment specifications is obtained according

to repair manual3. Adjusted carburetor according to required procedure


WORKPLACE:1. Learning resource area2. Workstation

EQUIPMENT/TOOLS:1. Gasoline engine mock-up (carbureted)2. Hand tools3. PPE


CDs, Related books)

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


METHODOLOGIES:

1. Self-paced instruction2. Demonstration

ASSESSMENT METHOD:1. Practical demonstration

LEARNING EXPERIENCES

LEARNING OUTCOME #4: PERFORMING CARBURETOR ADJUSTMENT



ADJUSTING ENGINE IDLE SPEED





TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


JOB SHEET#9.4-1

ADJUSTING ENGINE IDLE SPEED

PERFORMANCE OBJECTIVES:

After reading this job, you must be able to:

1. Use appropriate tools in adjusting engine idle speed;

2. Adjust carburetor to specification;

3. Apply occupational safety and health standards in the workplace.


EQUIPMENT:

1. PPE

2. Gasoline engine (carbureted)

TOOLS:

1. Tachometer

2. Screw drivers

3. Feeler gauge

MATERIALS:

1. Learning media (module, service manual, related books, computer set)

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


2. Clean rags

PROCEDURE:

Note: The correct idle speed adjustment is important with any carburetor, which is a complicated part for any gasoline engine. Some late carburetors have three separate fuel circuits in them (only two in older carburetors), and the 850-900 rpm idle is designed so the airflow through the carburetor is balanced for the idle circuit fuel flow. That's why it has both Volume and Bypass screws in the side (the earlier ones had only Volume screw), located on the left side of the carburetor. This way the idle speed can be set correctly using the Bypass screw without touching the screw on the throttle arm, which has to be set exactly right.

Refer to the exploded view as you go on.

1. Make sure that all the hoses are in place and the gasket at the base of the carburetor is sealing properly (no vacuum leak).

2. Install the air cleaner

3. Turn on the engine and run it until it is warm, then switch it off.

4. The first step is to set the throttle plate. Back off the Fast Idle Adjuster (also called the throttle screw) located at the top of the throttle arm. You will find the throttle arm on the left side of the carburetor, connected at the bottom to the accelerator cable, which runs forward to the accelerator pedal.

Note: Fast Idle Adjuster is NOT used to adjust the idle speed. The Fast Idle Adjuster works with the choke to give a smooth idle on a cold engine. As the choke warms (in concert with the warming engine, hopefully) the butterfly valve in the throat of the carburetor opens and the Fast Idle Adjuster screw moves down the steps of the choke fast idle cam, reducing the engine idle speed. Screwing the Fast Idle Adjuster screw in more will increase the idle speed, but doing so messes up the Volume Control and Bypass Screw adjustments. This destroys the idle

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


geometry, and the car won't run right.

5. With the choke held in the full open position (stepped cam at its lowest point), place a 0.003" feeler gauge between the lowest step of the choke fast idle cam and the Fast Idle Adjuster screw.

6. Slowly turn the screw in until you feel drag on the feeler gauge. Then remove feeler gauge and turn the screw in precisely 1/2 turn - no more! This sets the throttle butterfly open the required 0.004", so you can use the Bypass Screw to set the idle speed correctly. From this point on, leave the Fast Idle Adjuster screw alone.

7. Next set the volume of gas available at idle speeds. This is done using the Volume Control Screw. Please note that the Volume Control Screw controls the AIR volume, not the fuel volume. Screwing it in reduces the air and makes the fuel/air mixture richer. And of course turning the Volume Control Screw out increases the concentration of air and makes the mixture leaner.

Note: The Volume Control Screw is the smaller of the two adjusting screws, located on the left side of the carburetor just above the Idle Cutoff solenoid (which has a black wire from the positive side of the coil attached to it). The Volume Control Screw is NOT used to set the idle speed - that's the job of the Bypass Screw.

Note: Before setting the Volume Control Screw per the step below, turn the Bypass Screw (the larger one) out a couple of turns, just to get things started.

8. Screw the Volume Control Screw in GENTLY until it sits. Never screw it in tightly; you will destroy the seat. Now unscrew it exactly 2-1/2 turns. This is the initial setting.

Note: Be sure that the Volume Control Screw firmly seated, you may have trouble adjusting the idle with the Bypass Screw if it does not properly seated. This condition will cause stumbling on acceleration if not corrected.

9. With the Volume Control Screw out 2-1/2 turns, start the engine and let it warm up. (Make sure the choke is fully open.)

10.Now to set the idle. This is done by controlling the volume of air going by the Bypass Screw. The Bypass Screw is larger than the Volume Control Screw and is located a little above and to the left of the Volume

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


Screw.

Note: Again, the idle speed is NOT set with the Fast Idle Adjuster on the top of the throttle arm as it is on the older carburetors - though its name (Fast Idle Adjuster) would lead you to think that it is used to set the idle. It is not used to set the idle.

11. Connect a tachometer to the engine as detailed in the manufacturer's instructions.

On models having a conventional ignition system, one lead (usually black) goes to a good chassis ground. The other lead (usually red) goes to the distributor primary side of the coil (the terminal with small wire running to the distributor body).

On models with transistorized ignition, connect one lead (usually black) of the tachometer to a good chassis ground. Connect the other lead (usually red) to the negative (-) coil terminal, NOT to the distributor or positive (+) side. Connecting the tachometer to the wrong side will damage the switching transistor.

12.As a starting point, turn the idle Bypass Screw out to set the idle at 850 rpm (fast idle). For a semi-automatic car, use 900 rpm. It is better to start from a little bit higher rpm going down than to start from low rpm up.

13.With the engine warmed up and the choke fully open, go back to the Volume Screw and adjust it slowly to obtain the fastest (smoothest running) idle speed (this is usually out - counter-clockwise). You should not turn the screw out much outside the range of 2-3 turns (1/2 turn in/out from the basic 2-1/2 turn out setting).

14.Then turn the Volume Control screw back IN (clockwise) very slowly until the engine speed drops by about 20-30 rpm (slightly leaner). Look at your tachometer. If you don't have a tachometer, listen until you can just hear the engine speed start to drop, maybe as little as 1/8th turn on the Volume Screw.

15. Go back to the larger Bypass screw again to reset the idle speed to 850 - 900rpm. (Again, the fast idle is better than too slow. You want it just a little on the rich side. Too slow of an idle speed can cause the engine to overheat.)

Note: If you find it difficult or impossible to make these settings, it is possible that you could have stripped threads on any of these

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


adjusters, a damaged hole for the tapered screw, or a damaged needle valve or O-ring.

It is also possible that you have a vacuum leak (i.e., leaking of air into the intake manifold). If there are any holes in the manifold or at any of the connection points, then air can be sucked into the manifold, causing the fuel-to-air mixture to become too lean. This can cause (among other things) adjustment of the carburetor impossible.

ASSESSMENT METHOD


Acceptability

Yes No

1. Appropriate tools are used in adjusting carburetors ______ ______

2. Carburetor adjustment specifications is obtained according to repair manual

______ ______

3. Adjusted carburetor according to required procedure ______ ______


TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:




DEFINITION OF TERMS

1. Actuator- a control device that delivers mechanical action. In the mechanical fuel pump, this is called actuating lever.

2. Air cleaner- a device connected at the top of the carburetor to filter incoming air, making it clean before it mixes with the fuel.

3. Air pump- a device to produce a flow of air higher than atmospheric pressure.

4. Ambient air- temperature of air surrounding an object.5. Atomization- the stage in which the metered air-fuel emulsion is drawn

into the air stream in the form of tiny droplets. Atomized mixture is combustible.

6. Camshaft- the component in the engine that opens and closes the valves. It also operates the mechanical fuel pump.

7. Carburetor- a fuel delivery device that mixes fuel and air to the proper ratio to produce a combustible mixture.

8. Compression stroke- the second stroke of the four stroke engine cycle, in which the piston moves from bottom dead center and the intake valves close. This traps and compresses the air-fuel mixture in the cylinder.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


9. Detonation- as used in automobiles indicates a hasty burning or explosion of the mixture in the engine cylinders. It becomes audible through vibrations of the combustion chamber walls and is sometimes confused with a ping or spark knock.

10. Diaphragm- a flexible, impermeable membrane on which pressure acts to produce mechanical movements. In the mechanical fuel pump, the diaphragm creates pressure.

11. Ethanol- a widely used gasoline additive known for its abilities as an octane enhancer.

12. Filler neck- a tube fitted to the fuel tank that allows fuel to be added from a remote location.

13. Flooding- a condition in which excess, unvaporized fuel in the intake manifold prevents the engine from starting.

14. Fuel filter- a device located in the fuel line to remove impurities from the fuel before it enters the carburetor or injector system.

15. Fuel gauge- a gauge that indicates the amount of fuel remaining in the tank.

16. Fuel pressure regulator- a device designed to limit the amount of pressure buildup in a fuel delivery system.

17. Fuel pump- a mechanical or electrical device used to move fuel from the fuel tank to the carburetor or injectors.

18. Gasket- a thin layer of material or composition that is placed between two mating surfaces to provide a leak-proof seal between them.

19. Gum- in automotive fuels, gum refers to oxidized petroleum products that accumulate in the fuel system, carburetor, or engine parts.

20. Heptane- a standard reference fuel with an octane number of zero, meaning that it knocks severely in an engine.

21. Hydrocarbons- particles of gasoline present in the exhaust and in crankcase vapors that have not been fully burned.

22. Ignitability- the property of a liquid with a flash point below 140 F (60 C).

23. Isooctane- a standard reference fuel with an octane number of 100, meaning that it does not knock in an engine.

24. Jet- a precisely-sized, calibrated hole in a hollow passage through which fuel and air can pass.

25. Lean- an air-fuel mixture that has more air than is required.26. Octane number- a unit of measurement on a scale intended to indicate

the tendency of a fuel to detonate or knock.27. Oxidation inhibitor- gasoline additives used to promote gasoline

stability by controlling gum and deposit formation and staleness.28. Rich- an air-fuel mixture that has more fuel than is required.

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


29. Stoichiometric- chemically correct. An air-fuel mixture is considered stoichiometric when it is neither too rich nor too lean. Stoichiometric ratio is 14.7:1, that is 14.7 parts of air for every 1 part of fuel.

30. Vapor- a substance in gaseous state. Liquid becomes a vapor when brought above the boiling point.

INSTITUTIONAL ASSESSMENT INSTRUMENT

EVIDENCE PLAN

Qualification Title AUTOMOTIVE SERVICING NC II

Unit of Competency SERVICING ENGINE MECHANICAL COMPONENTS

Module Title SERVICING GASOLINE FUEL SYSTEM

The evidence must show that the candidate…

Ways in which evidence will be collected (tick the box)

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


Ora

l in

terv

iew

Wri

tten E

xam

Dem

onst

rati

on

Port

folio

Access and use fuel octane rating information in accordance with manufacturer’s specifications.

x

Gather and interpret data from American Petroleum Institute

x x

Apply safety measures in dealing with gasoline fuels.

x x

Identify fuel pump types/classifications x

Remove and install fuel pumps according to prescribed procedures

x x x

Access and interpret technical data from manufacturer’s specifications

x

Use appropriate tools, materials, and equipment in accordance to industry standards

xx

Overhaul carburetor as per service procedures

x x

Adjust carburetor to specification x x

Observe occupational safety and health standards x

x

Candidate’s Signature

Date:

Facilitator’s Signature

Date:

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


RATING SHEET FOR DEMONSTRATION

Candidate’s Name:

Assessor’s Name:

Assessment Center:

Qualification:

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


Unit of Competency

SERVICE ENGINE MECHANICAL COMPONENTS

Module Title SERVICING LUBRICATING SYSTEM

Date of observation:

During the performance of skills, the candidate….

If yes, tick the box

Removed and installed fuel pumps according to prescribed procedures

Used appropriate tools, materials, and equipment in accordance to industry standards

Overhauled carburetor as per service procedures

Adjusted carburetor to specification

Observed occupational safety and health standards

Candidate’s Signature Date:


ORAL QUESTIONING CHECKLIST

Satisfactory response

The candidate should answer the following questions:

Yes No

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


What is the importance of gathering technical information especially when dealing with flammable liquids?

Gasoline fuel is a flammable liquid. What safety measures you must apply when handling such materials?

Why fuel pumps are not repaired but replaced as a unit?

You are going to replace your vehicle’s fuel pump. When you read the service manual, it is required to disconnect the negative battery cable before proceeding. Why do you need to remove the battery cable?

In installing mechanical fuel pump, what will happen to the pump when the engine runs if you forgot to put back the spacer?

The volume control screw of the carburetor is set at the factory. What technique you can apply in removing it to simplify installation and to maintain the good performance of your carburetor?

What is the importance of using specifications manual?

In the performance of any job or work, what must you observe always to get it done without hurting yourself/anybody or damaging property?

The candidate’s underpinning knowledge was:

Satisfactory Not Satisfactory

Feedback to candidate:

The candidate’s overall performance was:

Satisfactory Not Satisfactory

Candidate’s Signature: Date:


TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


WRITTEN EXAMINATION

TRUE OR FALSE

Directions


1. _____ The chemical symbol for gasoline is C8H16, which indicates that each molecules of gasolines contains 8 carbon atoms and 16 hydrogen atoms.

2. _____ The lower the octane rating, the lesser of a tendency the engine has to knock.

3. _____ Two methods are used for determining the octane number of gasoline: the Motor Octane Number (MON) method and the Research Octane Number (RON) method.

4. _____The one displayed on gasoline pumps is the Antiknock Index (AKI). It is the average of RON and MON.

5. _____ A lean mixture burns slower than a rich mixture

6. _____ To reduce corrosion caused by sulfuric acid, the sulfur content in gasoline is limited to less than 0.01%.

7. _____ Methanol is the most widely used gasoline additive today.

8. _____ Blending 10% ethanol into gasoline result in an increase of 2.5 to 3 octane points.

9. ___Do not over-fill a container. Leave 10% extra space to allow for expansion.

10. ___ Gasoline vapors are flammable, heavier than air, and can travel long distances to an ignition source.

11. ___Refueling can always be done without turning the engine off.

12. ___ Drain tanks only in well-ventilated areas, preferably outdoors.

MULTIPLE CHOICE

DIRECTIONS

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:



___1. These pumps can be placed anywhere in the car, but work best when they are installed near fuel tanks. Newer fuel pumps of this type

are often located within the fuel tanks themselves.

A. automatic fuel pump

B. mechanical fuel pump

C. electric fuel pump

D. in-line fuel pump

___2. Mechanical fuel pumps are manufactured to operate at these pressures.

A. 4 to 6 psi

B. 2 to 3 psi

C. 6 to 8 psi

D. 8 to 10 psi

___3. The biggest difference between a mechanical fuel pump and electric fuel pump.

A. temperature output

B. pressure output

C. volume output

D. power output

___4. Mechanical fuel pumps are commonly used with this type of fuel system.

A. fuel injection type

B. port injection type

C. direct injection type

D. carbureted type

___5. This is installed between the mechanical fuel pump and the engine block to prevent oil leakage.

A. oil seal

B. gasket

C. spacer

D. washer

___6. It delivers fuel to the carburetor only when it is needed for the requirements of the engine.

A. electric pump

B. positive fuel pump

C. non-positive fuel pump

D. automatic fuel pump

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


___7. All of the following are locations where electric fuel pumps can be installed except one.

A. inside the fuel tank

B. as a part of the fuel pick-up sending unit

C. in line between tank and engine

D. in the engine

___8. This part of the fuel pump keeps the fuel from draining out of the fuel line when the pump is not in operation.

A. intake valve

B. outlet valve

C. check valve

D. control valve

___9. Impeller-type electric fuel pumps are located in this part of the fuel system.

A. main fuel line

B. inside the fuel tank

C. in the engine

D. in the carburetor

___10. Which of the following is not a cause of low fuel pump pressure?

A. leaking check valve

B. ruptured diaphragm

C. weak diaphragm spring

D. inoperative pressure relief valve (stuck closed)

ANSWER KEY

ORAL QUESTIONING

Possible/acceptable answers

1. It is important to gather technical information first especially when dealing flammables to avoid or prevent personal injury and damage to

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


property/environment.

2. When handling flammable liquids, be sure to put in a prescribed container and store in a safe place.

3. Fuel pumps are not repaired but replaced as a unit because their designs do not permit disassembly/assembly. Repairing such components is impractical because of their availability in the shop supplies.

4. Battery cable must be removed first before working on the fuel system to prevent accident. Gasoline vapors can catch electrical sparks which may result to fire or explosion. Prevention is very much important.

5. If you forgot to put the spacer back, the actuating lever of the mechanical pump will be damaged including the whole fuel pump unit.

6. If overhauling the carburetor requires removing the volume control screw, the best thing to do is count the number of turns until it goes out of its place. When you install it, just count again the turns.

7. Using specifications manual provides specific information regarding adjustments, tolerances, and other important information. Using manuals facilitates work and ensures good job.

8. Observe safety always: personal, property, and environment safety.

TRUE OR FALSE

1. FALSE

2. FALSE

3. TRUE

4. TRUE

5. TRUE

6. TRUE

7. FALSE

8. TRUE

9. FALSE

10. TRUE

11. FALSE

12. TRUE

MULTIPLE CHOICE

1. C

2. A

3. B

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


4. D

5. B

6. C

7. D

8. C

9. B

10. D

COMPETENCY ASSESSMENT RESULTS SUMMARY

Candidate’s Name:

Assessor’s Name:

Qualification: AUTOMOTIVE SERVICING NC II

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


Date of Assessment:

Assessment Center:

The performance of the candidate in the following assessment methods

[Pls. check () appropriate box]

Satisfactory

Not Satisfactor

y

A. Demonstration with Oral Questioning

B. Written Exam

Did the candidate's overall performance meet the required evidences/ standards

OVERALL EVALUATION COMPETENT NOT YET COMPETENT

Recommendation:

FOR RE-ASSESSMENT _____

FOR NATIONAL ASSESSMENT _____

General Comments [Strengths / Improvements needed]

Candidate’s signature:

Date:

Facilitator’s signature:

Date:

REFERENCES

1. Automotive Technology; Tech Manual; 4th Edition; ERJAVEC

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


2. Automotive Technology; 4th Edition; ERJAVEC

3. Toyota Training Manual

4. Auto Mechanics, Theory and Service By: de Kryger, Kobacik.Bono

5. Automotive Mechanics; 10th ed.Crouse: Anglin

6. Internet Websites

TESDA-MITQA

SYSTEM




Document No.

Issued by: of 110

Developed by:


Cblm Gasoline Fuel System

Documents

Transcript of Cblm Gasoline Fuel System